Scavenging device for combustion engines



J. C. MAcC. MACLAGAN.

SCAVENGING DEVICE FOR COMBUSTION ENGINES.

APPLICATION FILED AUG-16, 1921-.

1 ,42 1 2'7 3 Patented June 27, 1922.

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Specification of Letters Eatent.

Patented" June 27, 1922.

Application filed August 18, 1921. Serial No. 492,752.

To all ZU/LOII'L it may concern:

Be it known that 1, JOHN CAMPBELL MAC- Cxni. hilACIlAGAN, a subject ofthe King of Great Britain and Ireland, and a resident of Glasgow,Scotland, have invented certain new and useful Improved scavengingDevices tor Combustion Engines, for which I have received British PatentNo. 150,238 upon an application filed in Great Britain February 1920,and of which the following is the specification.

The invention which is applicable to combustion engines having pistonrods or tail rods has for its object to provide simple and effectivemeans for ensuring complete scavenging at the end of the working stroke,the means being applicable either alone or in conjunction with otherscavenging devices.

The improved device is of the type in which there is provided in thepiston or other rod, a portion of reduced diameter which is enclosed ina sleeve towards the opposite ends of which are series of ports. Thereduced portion thus serves asa means of communication between theports. The series of ports are arranged around the periphery ot' thesleeve, and the one series of JOI'tS are adapted to form communicationwith ports in the embracing wall of the cylinder cover, or in a sleevetherein, and so with an annular chamber therein, while the other seriesof ports are in communication with the interior of the cylinder.Scavenging air is supplied to the annular chamber and passes therefromthrough the ports in its walls and in the sleeve to the space within thesleeve and from thence to the interior of the cylinders at that point inthe travel of the rod at which the chamber ports and the coacting seriesof sleeve ports coincide. Now, it is apparent that were the sleeve portscommunicating with the cylinder in the same axial line as the sleeveports communicating with the chamber ports (and so in the same axialline as those ports) further motion of the rod would open communicationbetween the chamber ports and the first mentioned ports and so with theinterior of the sleeve and thence by way of the other sleeve ports withthe atmosphere. Either therefore, the distance between the two series ofports would have to be so great that the second series could neveroverrun the annular chamber ports or else an enclosing trunk would berequired to prevent connection between the cylinder and the atmosphere.

According to the invention therefore, the total width of each series ofports is made rather less than half the circumference of the sleeve andof the chamber wall, and while the one series of sleeve ports arepositioned to coact with the chamber ports, the other series (whichcommunicate with the cylinder) are made in axial line with the spacesbetween these ports, and so in passing the chamber ports do not opencommunication therewith.

An illustrative example of the carrying out of the invention is shown onan accompanying sheet of drawings, Figure 1 being a sectional elevationand Figure 2 a sectional plan on the line a-b in Figure 1.

In this example there is formed in the lower part of the piston rod A apart B of reduced diameter. This is enclosed by a sleeve C which is heldin position between the crosshead D and the lower end of the upper partE of the piston rod. Around its periphery is a series of ports F and aseries of ports G. The series of ports F communicate with the interiorof the cylinder, and the ports are in axial line with the walls betweenthe ports G which are adapted to coincide with ports H in a sleeve J inthe cylinder cover K, which ports communicate through its walls with anannular chamber L formed in the cylinder cover.

What I claim is 1. In an internal combustion engine, an explosioncylinder having at one end a chambered cover with a port opening to thechamber in the cover, a piston rod passing through said cover andrecessed in the portion thereof working in said cover, a casingenclosing said recessed portion of the piston rod, said casing beingapertured at longitudinally spaced points to alford portscircumferentially staggered with relation to each other, but opening tothe recess in the piston rod, the port toward the cylinder end of thecasing being out of axial alignment with the port in the cylinder cover,while the port toward the opposite end of the casing is located in axialalignment with the port in the cylinder cover and registers therewith inpredetermined longitudinal position of the piston rod to establishcommunication to the reduced portion of the cylinder rod,

while at its opposite end said sleeve has a series of ports located inaxial alignment with the ports to the cover chamber and registeringtherewith in predetermined longitudinal position of the piston rod toestablish communication between said chamber in the cylinder cover andthe explosion cylinder through the passageway afforded between thereduced portion of the piston rod and its enclosing sleeve.

In testimony whereof I have signed my name to this specification.

JOHN CAMPBELL MacCALL MACLAGAN.

